I remember the first time I was on W5R3. After 12 minutes I had to give up, reduce speed and go back at it.
Yesterday, for the first time after graduation, I felt the run a hard going one. I did manage the full 30 minutes. But it was harder than it has been before.
I had some fried spicy food for lunch and that had a big part to play in this. As a result, I am going to stay away from such food on my run days.
I felt very warm towards the end of the run - much more than every before. And I have decided to do all or at least, most of my future runs outdoors.
Strange that some runs would feel more difficult than others!